Cooling of blades in machines where blading is employed



BouLET Jan. 13, 1959 cooLING 0E BLADES 1N MACHINES WHERE BLADING IsEMPLOYED Filed Feb. 15, 195o '2 Sheets-Sheet 1 M E WARN@ Jan. 13, 1959G. BouLET 2,868,500y

COOLING oF BLADES V1N MACHINES WHEREk BLADING 1s EMPLOYD -Filed Feb.l15, 195o 2 sheets-sheet 2 ice COOLING OF BLADES IN MACHINES WHEREBLADING IS EMPLOYED `Georges Boulet, Toulouse, France ApplicationFebruary 15, `1950, Serial No. 144,229 `Claims priority, applicationFrance February 15, 1949 3 Claims. (Cl. 253-39.1S)

` My inventionrelates` to machines provided with sets of blades,jwhethercarried by 'a stationary or a moving part of the machine, in particularto turbines, compressors, and more particularly to machines havinginternally cooled hollow blades. t

An object of my invention is to provide cient cooling of the blades.

Another object is to provide for an eflicient and well ruled circulationof cooling fluid through the various blades. j

A further object in the case of multistage machines is to transfer `heatfrom a stage to another by means of an innerfluid circulation throughthe blades from the most heated stage to the less one. Once this objectattained, a still further object is then to provide multistage machinesadapted to operate nearly isothermically, and in particular a nearlyisothelmidmultistage compressor.'

Still another object is to provide machines having at least one bladewheel` the blades of which are cooled by an inner circulation of coolingfluid, and therefor blade wheels or barrels carrying blades cooled asjust said and which will be light, easy to machine and assemble,fluidtight and reliable in operation.

With these and other objects in view as will appear from the descriptiongiven `hereinafter ofvarious embodiments of` my invention, the latterconsists in the provision and combination of means, and arrangement ofparts, as will appear from said description and be more fully pointedout in the claims.

In the annexed drawings:

Fig. 1 is a section, through the axis, of a three-stage .'turbine of`which the stationary and moving blades are cooled; j t

Figs. 2, 3 and 4 are respectively cross-sections carried out at variousdistances from the axis of rotation alongthe lines II--IL III-Ill,` andIV-IV of Fig 1; j Fig. 5 is a diagrammatic end-view of a cooling devicefor stationary blades;

Figs. 6 and 7 are respectively cross-sections along the lines VI-VI andVII-VII of Fig. 1;

Fig. 8 is an elevational diagrammatic View of a turbocompressor with`cooled blades; and

Fig. 9 is a View similar to Fig. 8 of a modied embodiment of coolingmeans for the blades of a turbocompressor.

In the embodiment illustrated in Fig. l and that refers l toathree-stage turbine, each of the stagesV is provided, inthe usual way,with a" plate 1 to the periphery of which are fastened the blades 2 thatare hollow; each blade is fitted through its base with cross-section inthe shape of a parallelogram (Fig. 2) over a teat of the same shape cutinthe periphery of the plate 1, the base of the blade itself beingimbedded in the grooves formed between two adjacent teats. The spacebetween `two adjacentlplates is "closed by a rippled wall 3, in theshape of a surface of revolution, fastened to these two plates;

as shown the distance of said wall to the axis of rotation of theturbine wheel decreases from the rst stage, the blades of which are themost heated by the fluid flowing through the machine, to the otherstages the blades of which are less heated by said fluid. Outside thiswall is an outer ring 4 with U-shaped crosssection with its openingdirected towards the rotary aXis of the turbine and that is alsofastened to these ad jacent plates 1. A closed chamber 5 is thusprovided between two adjacent plates; the adjoining chambers are incommunication with each other through holes 6 going right through theplates in their central portion. A chamber '7 is arranged likewise onthe outer surface of the end plates andis demarcated by an outer surfacefof the plate and rippled wall 8 coveringthis surface and fastened tothe plate in question; this chamber 7 connects up also with the chambers5 through holes 6 arranged in the central portion of the end plates.Radial tubes 9, l0 project into each blade 2 and are arrangedrespectively with one nearthe leading edge of the blade and the othernear the trailing edge. These two tubes emerge in the neighborhood ofthe blade end the farthest away from the rotary aXis. They are fastenedin the rim of the plate carrying the blade, a rim through which they goto emerge in the chambers 5 or 7. Furthermore, each plate 1 is providedin register with each blade with a radial passage 12 hollowed out in thebody of the plate and that cuts one of the cross holes 6; it emerges onthe other hand substantially in the centre of the fastening teat fittedon the base of the blade. t It will be understood, under theseconditions, that if there is in the chambers 5 and 'l` and inside thehollowed blades a cooling fluid, the latter, as it is being heatedthrough the passing of the propelling jet between-the blades, willbecome heated more inside the blades than in the chambers 5 and '7 andthat, as` a consequence of the ensuing density variation, the denserfluid contained in the chambers 5 and 7 is centrifugalized through thetubes 9 and lll While the warmer and less dense yfluid is forced back bythe previous one through the passages 12 and 6 and returns into thechambers 5 and 7. There is thus self-circulation inside the blades. Itappears beneficial to make use of, as cooling uid, a material possessinga vapor# izing point that is less than the ordinary temperature of thepropelling jet. There thus takes: place a vapor.

ization inside the blades while the chambers 5 and 7 enclose thismaterial in the liquid or solid state. This material, for instance, maybe formed, to advantage, by metallic salts as in standard practice.

On the other hand, since the different chambers 5 and 7 link up witheach other, there' occurs between them a more or less well-markedequalizing of the temperature so that the heat removed in the firstblading set may be used to reheat the last lot of blading or several ofthe other blading sets and that there is thus automatic regeneration ofpower. It is therefor clear that the uid within the chambers 5 and 7 ieat a temperature less than that of the most heated blades but greaterthan that of the blades of the less heated stage or last stage.

Fig. l shows besides theaddition to the previous device of meansintended to cool the fluid that circulates in closed circuit in theblades. For this ptnpose, in the chambers 5 located between twoadjoining plates 1, there are arranged heat exchangers 14 formed in thiscase by annular flat chests with rippled wall carried by a centralhollow hub l5. Thisv hub is tted directly on the adjoining plates l. soas to form with them a continuous wall and the whole block of the platesand the hubs fitted on each other is held assembled toi gether throughlongitudinal stay-rods 16. The inside of the chest ill is incommunication through radial holes i7 and i8 with the inside of thehollow hub i5. A partition l@ inside the hub splits up the inner spaceof the latter into two divisions with no communication with each otherand this partition 19 is fastened to a central tube 2i) that isconcentric with the rotary axis and fastenedv to the body of the plate lof the rst stage. The inside of this tube is in communication, throughholes 2l, with the division 22 on the upllow side of the hub 16 whilethe other division 23 communicates freely round the tube 2li with thedivision 22 of the heat exchanger arranged in the adjacent chamber 5.

To the body of the plate of the last stage is fastened a tube 24 that isoutside and concentric with the tube with which it demarcates an annularpassage 25 in communication with the division 22 of the heat exchangerarranged between the penultimate and the last stage. gether, through theinstrumentality of revolving joints 26, to a stationary outer collector27 provided with a circular volute 2S, communicating With the annularpassage 25 and provided with an outlet pipe 29, and

a central passage 3o. The pipe 29 and the central passage 3i? areconnected through a pipe system, that is not shown, to means enabling acooling fluid to be delivered through the central passage 3@ into thetube 20 from where the fluid goes through the holes Zit into the headdivision 22 of the tirst exchanger 14, circulates inside the latter,leaves from it through the holes i8 into the division 23 from where itmakes its way into the second exchanger and leaves from the latterthrough the annular area 25 between the tubes Z0 and 24- and goes away,through the pipe 29 of the collector 27. Any suitable heat exchangermaybe inserted in the outer pipe system.

The stationary blades of the turbine shown in Fig. l are Vcooledlikewise. For this purpose, they are hollow and are provided with anextension that goes through the outer wall 36 of the annular jacketwhere the propelling jet circulates and these extensions are immersed ina common cooling casing 37 that surrounds this jacket of which the outerwall forms preferably one of the walls of this casing; pipes 3S and 39carried by this casing enable it to be connected through pipe systems,that are not shown, to means enabling a cooling liuid to be circulatedtherein, preferably in the same direction as that of the outliow of thepropelling jet as shown by the arrows in Fig. l. blades 3S are filledwith metallic salts in a pasty form adapted to be vaporized at atemperature lower than that of the propelling jet.

A modication of the cooling of the stationary blades of a turbine isshown in Figs. 5 and 9. In this modification, there enter into eachhollow blade two tubes di, 42 headed towards the axis of the blading andthat emerge inside the blade at two points that are at differentdistance from the axis. These two tubes 41, 42 are connectedrespectively to two dilerent collectors 43, i4 of annular shape and thatsurround the blading. The collector i3 is connected to the tube emergingnearest to the rotary axis and is of lesser cross-section than thecollector 44 into which converges the tube 4t2. The collectors 43 of thevarious bladings are connected up with a main pipe 45 while thecollectors 4d are connected to a pipe 46. Means not shown drive backinto the pipe 45 a cooling fluid, preferably of metallic salts in aliquid state, salts of sodium for example; this uid is delivered,through the passage 45, to the various collectors 43 and, through thelatter, to the tubes 4l of the different blades of each set of blading,then it leaves from these blades through the tubes 42 and is gatheredtogether in the various collectors 44 from `where it comes back throughthe general passage 46,

The tubes 20 and 24 are connected to- These stationary d by means thatensure its circulation. There is therefore in this case forcedcirculation inside the vanes. This mannerof carrying out the cooling ofthe stationary blades may be pointed out especially in the case of thinblades.

The various means as described for cooling the stationary blades and themoving blades of a turbine refer equally well to compressors, especiallyto axial compressors as shown in Figs. 8 and 9. In this case, however,in order to get as near as possible to isothermic compression, there isa separate casing 37a for the cooling of stationary vanes per compressorstage and these different casings are connected up in parallel on thedistributors 50, 5l for the inlet and outlet of a cooling fluid of whichthe` circulation is ensured by outer means connected to this distributorand that are not shown. Owing to this arrangement, the differentcompression stages may be kept substantially at the same temperature.

The same result may be secured in the case of cooling of the vanesthrough forced circulation and common feeding through a general passageas disclosed hereinabove for the turbine shown in Fig .9.

Instead of feeding the various bladings or the various collectorsthrough a distributor common to all the stages, each stage may be fedalso through a separate pipe system or else sets of several stages anduse may be made for each stage or each set of stages of a differentvolatile liquid suitable to the working temperature.

My invention, of coursejis restricted in no way to the details ofexecution as shown or disclosed, which have been given only as anexample. So it is that, without going outside the scope of theinvention, the stationary vanes of a compressor or of a turbine may becooled only or solely by the moving vanes.

In the caseof machines provided with a multistage blading two or morestages of hollow blades may also be serially connected in order that acirculation may be provided within the hollow blades from the moreheated stage to a less heated one.

What I claim is:

l. In a bladed uid ow machine required to run at high temperaturecomprising a rotary wheel, blades carried by the latter, at least someof which are each internally provided with a cavity enclosing a coolingmaterial of a nature such that it is within said cavity in a liuid stateat the normal running temperature of the rotary wheel, and heatexchanging means carried by said wheel and in operative cooling relationwith said cooling material to cool the latter, said heat exchangingmeans including a fluid tight chamber, and for each cooled blade atleast two ducts both communicating at one of their ends with saidchamber and at their other ends with the cavity of a blade, the emergingpoints of one of said ducts in the associated blade cavity and in saidchamber being respectively further remote from the wheel axis than thecorresponding emerging points of the other duct in said blade cavity andin said chamber.

2. In a machine as in claim l, wherein further said wheel bladingcomprises a plurality of cooled blade stages, said cooled blades of atleast two dilferent stages hav ing their respective ducts emergingin oneand the same huid tight chamber.

3. In a bladed fluid flow machine required to run at high temperaturecomprising a rotary wheel, blades carried by the latter, at least someof which are each internally provided with a cavity enclosing a coolingmaterial of a nature such lthat it is within said cavity in a fluidstate at the normal running temperature of the rotary wheel, and heatexchanging means carried by said wheel and in operative cooling relationwith said cooling material to cool the latter, said heat exchangingmeansv including a tluid tight chamber in communica@ tion with saidblade cavities and containing said cooling material, said rotary wheelcomprising a plurality of cooled blade stages, the cooled blades of atleast two different stages having their respective cavities incommunication with the same chamber.

References Cited in the file of this patent UNITED STATES PATENTS1,601,402 Lorenzen Sept. 28, 1926 1,938,688 Brooke Dec. 12, 19331,960,810 Gordon May 29, 1934 6 Noack July 10, 1934 Darrius Mar. 7, 1939Planiol et a1 Feb. 20, 1945 Halford June 11, 1946 Constant Aug. 28, 1951FOREIGN PATENTS Great Britain May 24, 1949 France Mar. 29, 1945

